Comminuting mill



March 15 1927. 1,620,982

R. C. NEWHOUSE GOMMINUTING MILL Filed April 15 1926 2 sheets-Sheet l March 15 1927. 1,620,982

R. C. NEWHOUSE COMMINUTING MILL Filed April 15. 1926 2 Sheets-Sheet 2 k\ E f/A y 7 V w l II.. I

Patented Mar. 15, 1927.

UNITED STATES PATENT OFFICE.

. l I I BAY C. NEWHOUSE, OF CHICAGO, ILLINOIS, ASSIGNOR TO ALLIS-CHALMERS MANU- FACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OE DELA- WARE.

COMMIN'UTING MILL.

This invention relates in general -.to improvements in the art of reducing relatively hard substances to pulverulent condi tion by impact and abrasion, and relates more specifically to improvements in the construction and operation of rotary drum mills for comminuting materials with the aid of a plurality of tumbling bodies cascading within the rotating drum.

An object of the invention is to provide an improved comminuting mill which is simple in construction and efiicient in operation and which afl'ords an exceptionally wide range of reduction.

'. It has heretofore been proposed to providea so-called combination drum mill divided into a succession of coarse and line grinding chambers by means of one or more partitions. more efficient reduction of relatively coarse material is obtainable in a preliminary grinding chamber operated at a relatively high rate of speed and cooperating with a fine grinding chamber of greater length operated at a con siderably lower rate of speed. While mills have heretofore been constructed in which the diameter of the preliminary grinding chamber was considerably greater than that of the fine reduction chamber, the variation in diameter of the two chambers of these prior mills was abrupt. It has been found that a relatively gradual change in diameter, and hence in the speed of operation, of the coarse and fine grinding chambers at the place of mergence of the one with the other, produces more eflicient reduction of the material. It is an object of the present invention to provide a combination mill having coarse and fine grinding chambers joined by a gradually tapered connecting portion so that the material undergoes a gradual and uniform reduction While passing from chamher to chamber.

The present invention also contemplates an improved system of comminuting material and of insuring delivery from the system of sufficiently comminuted materials only. In accordance with the improved system all material delivered from the mill which is insufficiently ground, is automatically returned for further reduction.

These and other objects and advantages will appear in the courseof the following description. 7 7

It is a well known fact that' Application filed April 15, 1926. Serial No. 102,120.

A clear conception of an embodiment of the invention and of the operation of devices constructed in accordance therewith,'may be had by referring to the drawings accompanyingand forming a part of this spe'ci-- fication in WhlCh llke reference characters tion of the improved combination comminuting mill.

The combination commin'uting mill comprises in general a rotary drum which is divided into coarse and fine grinding chambers 3, 4 respectively by means of a transverse division head or partition; feed and discharge trunnions 28, 24 rotatably supporting the drum at its ends; and a gear 9 or other suitable'means for continuously rotating the drum about its longitudinal axis. The coarse grinding chamber is located directly adjacent to the feed trunnion 23 and receives its supply of raw material from a feed mechanism 5, through the trunnion 23. The preliminary grinding chamber 3 is in closed by a cylindrical shell portion 17 of relatively large diameter, by an end head at-' tached to one end of the shell portion 17, by

a tapered shell portion 18 attached to the opposite end of the cylindrical portion 17,

and by the divisionihead which is provided with discharge screens 26 located at the smaller end of the tapered portion 18. A charge of relatively large freely tumbling comminuting bodies or balls2O is located .longitudinal section through the medial porwithin the coarse grinding chamber 3, the;

perforations of the screen 26 being too small to permit passage therethrough of the balls 20, While permitting free delivery otcomminuted material. The division head or partition comprises a transverse wall coo erating with the screen 26 to form a disc arge space .17 which communicates wlth an annular screening chamber surrounding the drum and surrounded by a screen 7 Spreaders 28 located within the screening chamber serve to distribute the material delivered from the chamber'3, over the screen 7 as the mill revolves, and the space 27 is provided with several return passages 25 to which rejects from the screen 7 are delivered by means of scoops 32 and which in turn return these rejects to the chamber 3 for further reduction. The fine rindingchamber 4 is located on the side 0% the division head opposite to the coarse grinding chamber 3, and extends up to the' discharge trunnion 24. The chamber 4 is supplied with material from a' receptacle 19 located below the screen 7, by means of peripheral scoops and njectors 29 which deliver the preliminarlly reduced material into the chamber 4 closely adjacent to the division head. The chamber 4 is inclosed by a relatively long cyllndrical shell portion 2 of'considerably smaller dlameter than the portion 17, by a discharge end head attached to one end of the portlon 2 and to the trunnion 24, and by, the division head located at theopposite end of the shell portion 2. A charge of relatively small freely tumbling comminuting bodies 21, such as concavex, is located within the chamber" 4 and a hold back'screen 22 serves tQpermit free discharge of comminuted .material while preventing discharge of the bodies 21 to the trunnion 241 The shell portions 2', 17 18 may be provided with suitable liners 31, and the receptacle 19 is preferably provided with a clean-out 30 as shown in Fig. 3.

I The discharge trunnion 24 communlcates with adischarge chamber 6 from which relatively fine material and air are withdrawn through a suction conduit 10 leading to. a ba type dust collector 12, while coarser partic es are removed by means of a bucket elevator 11. The elevator 11 is forined to deliver the relatively coarse particles to a centrifugal separator 15 through a spout 14, and the separator 15 is adapted to separate the sufficiently comminuted material from the oversize in a well known manner. The oversize material discharged by the separator 15 is conveyed to the receptacle 19 for further reduction by means of a conduit 16, while the final product is delivered from the separator 15 directly to a final discharge conveyer 13. The bag type dust collector 12 likewise discharges the material separated from the air passing therethrough, directly to the conveyer 13, and a single fan 33 or other suctiom device serves to draw dust laden air from the mill through the conduit 10 and dust collector 12, and to deliver the purified air from the comminuting system.

During normal operation of the installation, the raw material is fed through the trunnion 23 into the coarse grinding chamber 3 of the rotating drutn, by means'of the continues to rotate, the scoops 8 intermittently pick up charges of the material in the receptacle 19 and deliver the same into the.

end of the fine grinding or finishing chamber 4 closely adjacent to the division head."

In the 'chamber 4, the relatively line material is further reduced to a finepowder by the abrasive action of the relatively small freely tumbling comminuting. bodies 21. The fan 33 draws air through the finishing chamber 4and this blast of air picks up particles of fine material and carries them through the hold back screen 22 and through the trunnion 24 into the chamber 6 wherein the relatively heavier particles gravitate into. the buckets of the elevator 11 while the air with the lighter particles in suspension passes through the' conduit 10 to the dust collector 12: The material which is picked up by the elevator 11 is eventually delivered to these arator 15 which separates the fine product rom the oversize, the former being ischarged' to the final conveyer 13 and the latter being returned 'to the receptacle 19 for further reduction in the chamber 4.

The dust collector 12 separates the fine prodnot from the air blast, and likewise deposits the separated material in the conveyer 13. It will thus be noted that the comminuting system effectively reduces the material to a desired fineness and that oversize material is effectively separated and returned to the mill for. further reduction.

By forming the drum of larger diameter at its inlet end, the large comminuting balls 20 are enabled to more effectively perform their impact function due to thehigher peripheral speed of the chamber 3 and to the higher drop of cascade. The tapered connecting portion 18 of the drum provides a zone of gradual reduction connecting the chamber-3 with the chamber 4. \Vhile this tapered portion has been illustrated as. being located on the coarse chamber side of the division head, it may obviously be disposed on the opposite side of the head if so desired. The tapered connecting portion 18 furthermore produces a stronger section for the shell and causes the balls 20 to grade themselves according to size within the taper. It should be understood thatit isfl desired to limit the invention to the exact details of construction and operation herein shown and described, for various modifications within the scope of the claims may occur to persons skilled in the art.

It is claimed and desired to secure by Letters Patent:

1.-In a comminuting mill, a cylindrical shell portion forming a preliminary reduc,

tion chamber, a cylindrical shell portion of smaller diameter forming a final reduction chamber, a tapered shell portion connecting said cylindrical shell portions, and freely tumbling comminuting bodies located within each of said shell portions. i.

2 In a comminuting mill, a cylindrical shell portion forming a preliminary reduction chamber, a cylindrical shell portion of smaller diameter forming a final reduction chamber,a tapered shell portion connecting said cylindrical shell portions, all of said shell portions being disposed concentric with respect to and rotatable about a 'common axis, and freely tumbling comminuting bodies located within each of said shell portions, the comminuting bodies in the preliminary reduction chamber having characteristics differing from those in thefinal reduction chamber.

'31'In a comminuting mill, a cylindrical shell portion forming a preliminary reduction chamber, a cylindrical shell portion of smaller diameter forming a final reduction chamber, a tapered shell portion connecting said cylindrical shell portions,- all of said shell portions being disposed concentric with respect to and rotatable about a common axis, and freely tumbling comminuting bodies located within each of said shell portions, the comminuting bodies in the preliminary reduction chamber being larger and heavier than those in-the final reduction chamber.

. 4. In a comminuting mill, a single shell forming a comminuting chamber comprising cylindrical end portions of different diameters and a tapered intermediate con-- shell portion forming a preliminary reduction chamber, a cylindrical shellportion of smaller diameter forming a finalreduction chamber, a tapered shell portion connecting said cylindricalshell portions, a partition spanning the interior of said mill to segre gate said preliminary and final redaction chambers, and freely tumbling comminuting bodies located within each of said chambers.

6. In a comminuting mill, ashell comprising two cylindrical end portions of different diameters and an intermediate tapered connecting portion, a partition within said shell adjacent to said tapered portion, freely tumbling comminuting bodies located within each of said shell portions, means for introducing material intosaid shell portion of largest diameter, means for discharging comminute'd material from said shell -por-- tion of smallest diameter, and means for discharging material from said shell on one side of said partition and for returning some of said material to said shell on the opposite side of said partition.

7. In acomminuting mill,a shell forming segregated comminuting chambers, means i for feeding material into one of'said chambers, means for delivering comminuted material from the other of said chambers, a pneumatic separator for treating the material delivered from said other chamber, and means for introducing rejects from said separator into said other chamber.

8. Ina comminuting mill, a shell forming segregated comminuting chambers of different diameters, means for introducing material into said chamber having largest diameter, means for delivering material from said chamber having largest diameter and for introducing a part of said material into said chamber of smallest diameter, means for delivering material from said chamber of smallest diameter, a separator for treating the material delivered from said chamber of smallest diameter, and means for returning the rejects from s aid separator to said chamber of smallest diameter with the material introduced thereto from said chamber of largest diameter. 1

9. In a comminuting mill, a shell forming a comminuting chamber comprising two cylindrical portions of different diameters and a tapered connecting portion, a plurality of relatively large freely tumbling comminuting bodies disposed Within said portion of largest diameter, and a plurality .of relativelysmall freelytumbling commlnuting bodies disposed within said portion of smallest diameter.

In testimony whereof, the signature of the inventor is affixed hereto.

- RAY C. NEWHOUSE. 

